The instant invention relates to a plastic fuel tank for combustion engines. More particularly, the instant invention relates to a plastic fuel tank comprising a large main tank and a smaller collecting tank which is connected to the main tank via a flow-through opening located in the underside of the main tank.
The collecting tank to which the fuel suction line and the fuel return line are connected constitutes the fuel reserve which is required for trouble-free operation of the motor. This arrangement prevents air from being sucked into the fuel suction line, especially when the fuel level in the main tank is low and the brakes are applied, or the vehicle is accelerated or driven around curves.
In order to ensure the reliability of this function, the collecting tank has up to now been installed outside the main tank, i.e., beneath its underside (see, e.g., German Pat. No. PS 30 06 254) because a total utilization of the fuel reserve from the main tank appeared to be possible only if the collecting tank was located in this lowest position. However, such an arrangement of the collecting tank outside and below the main tank has obvious disadvantages, especially if the fuel tank is located on the outside of the vehicle near its underside. In this position, the collecting tank is exposed to excessive unevenness in the road, obstacles on the road, ice accumulations, etc.
Even when the fuel tank is located within the vehicle, as is the case more and more often in modern vehicles, a collecting tank located outside the main fuel tank is seen as a disadvantage because it affects optimal utilization of the space available for the main tank. Such an arrangement also reduces the amount of fuel in the main tank which can be theoretically used.
It is therefore an objective of the instant invention to design a plastic fuel tank in such manner that it can be built by a blowing or blister process and has improved spatial characteristics while ensuring reliable fuel supply to the engine and eliminating the disadvantages of known fuel tanks.